Process of making paper-pulp from straw.



. general UNITED STATES PATENT OFFICE.

LUDWIG KARL B6HM, OF'JERSEY CITY, NEW JERSEY.

IBOOESS 01 me PAPER-PULP FROM STRAW.

No. s70,s1s.

Specification of Letters Patent.

Patented Dec. 31, 1907.

To all whom it maflfconcerm 'Be it known that I, Lunwro KARL Bonn,

a citizen of the United States of America,

fication.

This invention has reference. to certain new and useful improvements inrocess of making paper pulpfrom straw. t pertains particularly to animprovement in a novel process of making aper pulp from straw in which anew bleac ling process is em loyed whereby straw pulp is obtained which,as well as the paper made therefrom, remains always white withoutbecoming slightly yellow, as is the case with certain pulps and papersheretofore made.

he increasing importance of making paper pul from straw at the presenttime is recognized. The trees from which the wel known sulfite (pulp ismade, grow eath in 30-40 years an consequently cease to be in the futuresuch a great resource of aper material as it has been in the past. t iermaterials for pa er pulp such as sugar cane com stalk, and eaves ofexotic plants yield a variable percentage of pulp because when cut, someare over ri e whileothers have not yet fully develope Particularly thelatter are not yieldin a commercial percentage of fiber because t ey arestill fleshy. Paper manufactured wholl or partly from straw ulppossesses a big degree of snap and e asticity. Cards made of same arehighly elastic, when bent they issue an a seab 0 cracklin sound andreturn uic y to their origins position. If suitab y colored the cardsresemble the well known elastic ivory cards which are very expensive.

It is a daily observance that white paper from various makes etsyellowish in the course of time. This is due to the resence of alkalinesubstances adhering to t e fiber. In order to be useful for hi h gradesof paper, straw pulp must not only 0 fine and white, but the paper madeof same must remain white in the course of time.

To obtain fine and white straw pulp from which paper may be made whichdoes not get yel owish in the course of time, I substantially proceed asfollows: Half stuff of straw is first produced in accordance to theprocess described in my Letters Patent #659,784 of October 16, 1900.When the required fineness for half stuff has been reached the liquid isdrawn off and 3% solution of oxalid acid introduced into the hollanderand the same set. to work again.. By this treatment the entire fiber isim regnated with oxalid acid. The purpose 0 this treatment will be aparent further on. The half stuff is now bleached in the bleaching tanksor the excess of liquid may be drawn off and the bleaching 'donedirectly in the hollander. The bleaching is ell'ected by a freshlyprepared solution of hypochlorite of magnesia. The fiber impregnatedwith oxalic acid is attacked by the bleaching solution. When thebleaching agent enters the fiber it is directly decomposed by the oxalicacid and the chlorine acts energetically in the 'nascent state on thefiber without ractically any loss whereby a nick and ef ective bleachingtakes place. perfectly white. Should some oxala te oi magnesium be formean remain in the fib'r's'mdoes'notdoany harm because it is anindifferent white powder and acts as a filler, however durin thesubsequent breaking and washing of t is fiber most of it settles and iswashed out as it is sli htl soluble in water. The saturation of t e iberwith a weak solution of oxalic acid brings about a white product whichlooks shin At the same time all the traces of free a ali adhering to thefiber are transformed into oxalate of sodium for instance which is vereasily solubleand quickl washed out. This is important because t etraces of alkali sticking to the fiber produce the yellowish appearanceof the aper in the course of time. In glace of oxa 1c acid tartaric acidmay be used.

xalic acid, however, is preferable because it is composed of twocarboxyl grou s. The half stufi is now transferred into tie T eresulting fiber is r fiber breaker and disintegrated to fine pulpmagnesia, producing thereby oxalate of mag- "half stuff by a solution ofhypochlorite of meant and producing the fine pulp by d.isinte-'magnesia, producing thereby oxalate of maggratin the half stuff. nesla,disinte 'rating'the half -stuff to fine 2. T e improvement in theprocess of makpup, and w'orlzing the fine pulp up into paper. ing paperpulp from straw consistingin proigned at New York, N. Y., this 11th day1 (lucing haf stuff from straw by means of of March, 1907. fixedalkalies, treating. the half stuff with an LUDWIG KARL BOHM.

oxalic acid solution, agitating the half stuff in Witnesses: the oxalicacid solution so as to com letely FRANK JORDAN, 10 impregnate the fibertherewith, bleachmg the LOUISE M. BOERLAGE.

